I Knew Sir James Mackenzie Davidson personally, and he was always an inspiration to us in those early days of radiology.I remember well once asking him how he got such good results in his kidney cases, and his answer was, “One tube for each case.” Tubes were then seventeen and sixpence each, so that answer could hardly apply nowadays.Mackenzie Davidson was always trying to-day to do something which seemed impossible, to-morrow he succeeded. This was his constant attitude towards radiological problems and accounts in a large measure for his remarkable successes. I am sure my subject of to-day would have greatly pleased him.Mackenzie Davidson came prominently before us early radiologists by his invention of the motordriven paddle mercury break. Many of you probably have never seen or even heard of it. This, Fig. 1, is an illustration of it. I have one of his earliest models in what I call my “junk room,” and in which I have preserved all sorts of ancient apparatus. I should like here to suggest that in addition to our Mackenzie Davidson Library we should have a Mackenzie Davidson Museum.Mackenzie Davidson was the inventor of many other pieces of apparatus, including the cross thread localiser, which is so familiar to you all, and the lead-lined protective tube-box. The inspiration for the latter, I believe, came from the north.